1. Field of the Invention
The present invention relates to a rotor mechanism, more particularly, an improved rotor mechanism used in vacuum systems like a vacuum pump, an air compressor, a compressor, and those machines which includes a periodic compression operation of intake and exhaust, thereby providing enhancing those machines a high compression ratio and a smooth intake and exhaust process and avoiding noise and vibration.
2. The Prior Art
Referring to the U.S. Pat. Nos. 4,138,838, 4,224,016, 4,324,538, 4,430,050 and 5,149,256, the double lobes type rotor of multi-phases roots type compressor or vacuum pump relates to the present invention. Such double lobes type rotor mechanism comprises a pair of the intermeshing displacement rotor and valve rotor. A pair of lobes of each rotor provides periodic compression operation of air intake and air exhaust. Therefore, when intermeshing, the inosculation of two lobes of the rotors is very important. If the inosculation of the two lobes of the rotors is not good enough, noise and vibration may occur during the periodic air intake, air exhaust, and non-compression of the rotors. Moreover, wear may occur due to the improper intermeshing of the rotors thereby reducing the production useful life. The above-mentioned U.S. Pat. No. 5,149,256 obviously has those defects. Referring to FIG. 10, the lobes of a pair of rotors 8, 9 of U.S. Pat. No. 5,149,256 includes the tip portions 82, 92 formed at the junctions between the concave portions 80, 90 and the arcuated surface 81, 91 so that there is discontinuity of the rotors 80, 90""s curves at the tip portion 82, 92. Therefore, during the moments from inefficient compression period to the period of air""s starting intake, the top portions 83, 93 of the rotors 8, 9 will operate unsmoothly at the tip portion 82, 92 thereby resulting in noise and vibration.
To overcome those defects of the double lobes type rotor of the prior art, the object of the present invention is to provide an improved rotor mechanism which could operate smoothly and avoid noise and vibration during the periodic operation of intake, exhaust, and carryover, etc.
Another object of the improved rotor mechanism of the present invention is to provide an improved rotor mechanism which provides great displacement transference and high compression ratio to achieve the vacuum demanded for vacuum system by fewer stages of rotor sets in series. Therefore, such a improved rotor mechanism is cost efficient.
To fulfill the above-mentioned objects, the improved rotor mechanism of the present invention includes an improvement on the structure of the intermeshing displacement rotor and valve rotor, that is, to provide the two rotors a smooth operation curve during the carryover period. The main feature is that the operation curve provided by the displacement rotor and the valve rotor from the carryover period to the period of starting intake is defined by a couple of smoothly connected different curves rather than a couple of connected arcs.
Another feature of the improved rotor mechanism of the present invention is that the operation curve from the period of starting air intake to the period of ending provided by the displacement rotor and the valve rotor is defined by an arcuated surface thereby providing great displacement transference and high compression ratio.